Objectives. Rotator cuff tears are among the most frequent upper extremity injuries. Current treatment strategies do not address the poor quality of the muscle and tendon following chronic rotator cuff tears. Hypoxia-inducible factor-1 alpha (HIF-1α) is a transcription factor that activates many genes that are important in skeletal muscle regeneration. HIF-1α is inhibited under normal physiological conditions by the HIF prolyl 4-hydroxylases (PHDs). In this study, we used a pharmacological PHD inhibitor, GSK1120360A, to enhance the activity of HIF-1α following the repair of a chronic cuff tear, and measured muscle fibre contractility, fibrosis, gene expression, and enthesis mechanics. Methods. Chronic supraspinatus tears were induced in adult rats, and repaired 28 days later. Rats received 0 mg/kg, 3 mg/kg, or 10 mg/kg GSK1120360A daily. Collagen content, contractility, fibre type distribution and size, the expression of genes involved in fibrosis, lipid accumulation, atrophy and inflammation, and the mechanical properties of the enthesis were then assessed two weeks following surgical repair. Results. At two weeks following repair, treatment groups showed increased muscle mass but there was a 15% decrease in force production in the 10 mg/kg group from controls, and no difference between the 0 mg/kg and the 3 mg/kg groups. There was a decrease in the expression of several gene transcripts related to matrix accumulation and fibrosis, and a 50% decrease in collagen content in both treated groups compared with controls. Additionally, the expression of inflammatory genes was reduced in the treated groups compared with controls. Finally, PHD inhibition improved the maximum stress and displacement to failure in repaired tendons. Conclusions. GSK1120360A resulted in improved enthesis mechanics with variable effects on muscle function. PHD inhibition may be beneficial for connective tissue injuries in which muscle atrophy has not occurred. Cite this article: J. P. Gumucio, M. D. Flood, A. Bedi, H. F. Kramer, A. J. Russell, C. L. Mendias. Inhibition of prolyl 4-hydroxylase decreases muscle fibrosis following chronic rotator cuff tear. Bone Joint Res 2017;6:57–65. DOI: 10.1302/2046-3758.61.BJR-2016-0232.R1

Objectives

Rotator cuff tears are among the most common and debilitating upper extremity injuries. Chronic cuff tears result in atrophy and an infiltration of fat into the muscle, a condition commonly referred to as ‘fatty degeneration’. While stem cell therapies hold promise for the treatment of cuff tears, a suitable immunodeficient animal model that could be used to study human or other xenograft-based therapies for the treatment of rotator cuff injuries had not previously been identified.

Magnetic resonance imaging (MRI) is the gold standard for the diagnosis of the pathologies affecting the glenohumeral joint and the rotator cuff diseases. MRI allows to highlight anatomic discontinuities of both muscles and tendons. However, MRI diagnostic accuracy has not proven to be highly sensitive in distinguishing between a partial-thickness tear and a full-thickness rotator cuff tear. The purpose of this study was to determine if MRI under axial traction can be helpful in increasing MRI sensitivity to identify partial-thickness rotator cuff tears. The study included 10 patients (4 males and 6 females) who had clinical examination and MRI suggesting a partial-thickness rotator cuff tear. They were candidates for shoulder arthroscopy because of persistent symptoms after at least three months of conservative treatment. The patients underwent a new MRI (under axial traction: MRI-AT) with a 4-kg weight applied to the affected arm. Then the patients underwent arthroscopy to confirm the diagnosis. Patients with a suspected full-thickness rotator cuff tear were excluded from the study. Patients’ average age was 52.4 years, and the dominant side was affected in 77.7% of the cases. Preoperative Constant-Murley Score was 57. MRI-AT showed that 3 patients were affected by a complete tear of the rotator cuff, 3 patients by a partial-thickness rotator cuff tear and 4 patients had no lesion. The analysis of data showed that: under axial traction the subacromial space increased by 0,2 mm (P value = 0,001075), the superior glenohumeral space decreased by 2.4 mm (P value = 0,07414), the inferior glenohumeral space increased by 0.3 mm (P value = 0,02942), the acromial angle decreased by 1.9° (P value = 0,0002104) and the acromion-glenohumeral angle decreased by 0.3° (P-value = 0,01974). Two experienced evaluators analyzed previous standard MRI and MRI-AT scans in a double-blinded fashion, with inter-rater evaluation of all the images and measures. Intraclass correlation coefficient (ICC) has been utilized to assess the reliability of the measures performed by different operators. ICC always resulted in more than 0.7, showing a high concordance among values in the same group. A comparative evaluation between standard MRI and MRI-AT has been conducted to highlight possible discrepancies and this has been compared to intraoperative findings. Concordance of the values was 89% between standard MRI and MRI-AT and 100% between MRI under axial traction and intraoperative findings. This study showed a high correlation between the diagnosis achieved with MRI-AT and the intraoperative arthroscopic findings. The use of MRI-AT in clinical practice may improve the diagnostic sensitivity of this method to detect a partial-thickness rotator cuff tear

This study aims to investigate the mechanical properties of a rotator cuff tear repaired with a polypropylene interposition graft in an ovine infraspinatus ex-vivo model. Twenty fresh shoulders from skeletally mature sheep were used in this study. A tear size of 20 mm from the tendon joint was created in the infraspinatus tendon to simulate a large tear in fifteen specimens. This was repaired with a polypropylene mesh used as an interposition graft between the ends of the tendon. Eight specimens were secured with mattress stitches while seven were secured to the remnant tendon on the greater tuberosity side by continuous stitching. Remaining five specimens with an intact tendon served as a control group. All specimens underwent cyclic loading with a universal testing machine to determine the ultimate failure load and gap distance. Gap distance increased with progressive cyclic loading through 3000 cycles for all repaired specimens. Mean gap distance after 3000 cycles for both continuous and mattress groups are 1.7 mm and 4.2 mm respectively (P = .001). Significantly higher mean ultimate failure load was also observed with 549.2 N in the continuous group, 426.6 N in the mattress group and 370 N in the intact group. The use of a polypropylene mesh as an interposition graft for large irreparable rotator cuff tears is biomechanically suitable and results in a robust repair that is comparable to an intact rotator cuff tendon. When paired with a continuous suturing technique, it demonstrates significantly resultant superior biomechanical properties that may potentially reduce re-tear rates after repairing large or massive rotator cuff tears

Re-rupture rates after rotator cuff repair remain high because of inadequate biological healing at the tendon-bone interface. Single-growth factor therapies to augment healing at the enthesis have so far yielded inconsistent results. An emerging approach is to combine multiple growth factors over a spatiotemporal distribution that mimics normal healing. We propose a novel combination treatment of insulin-like growth factor 1 (IGF-1), transforming growth factor β1 (TGF-β1) and parathyroid hormone (PTH) incorporated into a controlled-release tyraminated poly-vinyl-alcohol hydrogel to improve healing after rotator cuff repair. We aimed to evaluate this growth factor treatment in a rat chronic rotator cuff tear model. A total of 30 male Sprague-Dawley rats underwent unilateral supraspinatus tenotomy. Delayed rotator cuff repairs were then performed after 3 weeks, to allow tendon degeneration that resembles the human clinical scenario. Animals were randomly assigned to: [1] a control group with repair alone; or [2] a treatment group in which the hydrogel was applied at the repair site. All animals were euthanized 12 weeks after rotator cuff surgery and the explanted shoulders were analyzed for biomechanical strength and histological quality of healing at the repair site. In the treatment group had significantly higher stress at failure (73% improvement, P=0.003) and Young's modulus (56% improvement, P=0.028) compared to the control group. Histological assessment revealed improved healing with significantly higher overall histological scores (10.1 of 15 vs 6.55 of 15, P=0.032), and lower inflammation and vascularity. This novel combination growth factor treatment improved the quality of healing and strength of the repaired enthesis in a chronic rotator cuff tear model. Further optimization and tailoring of the growth factors hydrogel is required prior to consideration for clinical use in the treatment of rotator cuff tears. This novel treatment approach holds promise for improving biological healing of this clinically challenging problem

We performed this systematic overview on the overlapping meta-analyses that analyzed autologous platelet-rich plasma (PRP) as an adjuvant in the repair of rotator cuff tears and identify the studies which provide the current best evidence on this subject and generate recommendations for the same. We conducted independent and duplicate electronic database searches in PubMed, Web of Science, Scopus, Embase, Cochrane Database of Systematic Reviews, and the Database of Abstracts of Reviews of Effects on September 8, 2021, to identify meta-analyses that analyzed the efficacy of PRP as an adjuvant in the repair of rotator cuff tears. Methodological quality assessment was made using Oxford Levels of Evidence, AMSTAR scoring, and AMSTAR 2 grades and used the Jadad decision algorithm to generate recommendations. 20 meta-analyses fulfilling the eligibility criteria were included. The AMSTAR scores of the included studies varied from 6–10 (mean:7.9). All the included studies had critically low reliability in their summary of results due to their methodological flaws according to AMSTAR 2 grades. The initial size of the tear and type of repair performed do not seem to affect the benefit of PRPs. Among the different preparations used, leucocyte poor (LP)-PRP possibly offers the greatest benefit as a biological augment in these situations. Based on this systematic overview, we give a Level II recommendation that intra-operative use of PRPs at the bone-tendon interface can augment the healing rate, reduce re-tears, enhance the functional outcomes and mitigate pain in patients undergoing arthroscopic rotator cuff repair

Introduction. Glenoid inclination, defined as the angle formed by the intersection of a line made of the most superior and inferior points of the glenoid and a line formed by the supraspinatus fossa, has been postulated to impact the mechanical advantage of the rotator cuff in shoulder abduction. An increase in glenoid inclination has previously been reported in patients with massive rotator cuff tears and multiple studies have correlated rotator cuff tears to an increase of the critical shoulder angle, an angle comprised of both the glenoid inclination and acromical index. Glenoid inclination is best measured by the B-angle as it has been shown to be both an accurate and reliable. The purpose of this study was to determine the correlation of glenoid inclination and the presence of degenerative rotator cuff tears. Methods. Data was prospectively collected for study patients assigned to one of two groups. The tear group consisted of patients with degenerative, atraumatic rotator cuff tears, confirmed by MRI and the control group consisted of healthy volunteers without shoulder pain. Inclusion criteria for both groups included age 45 or older. Exclusion criteria included history of previous shoulder surgery, previous patient-recalled injury to the shoulder, presence of glenoid weak, and previous humerus or glenoid fracture. Patients were also excluded from the control group if any shoulder pain or history of rotator cuff disease was present. All patients had standard anterior/posterior shoulder radiographs taken and glenoid inclination was digitally measured with Viztek OpalRad PACS software (Konica Minolta, Tokyo, Japan). The beta angle was measured to determine the glenoid inclincation. Statistical analysis was performed using SPSS version 23 (IBM, Aramonk, NY). Patient age and glenoid inclination were examined with the Shapiro-Wilk test of normality and then compared with student t tests. Gender distribution was compared with chi square test. A p-value of 0.05 was used to represent significance. Results. The study included 26 patients in the tear group and 23 patients in the control group. There was no difference in the age of the two groups (57 vs 54, p=0.292) or gender distribution (p=0.774). The average glenoid inclination was 11.18 (SD=2.67) degrees for the tear group and 5.97 (SD=2.55) degrees for the control group. This difference was statistically significant (p<0.001). Discussion. Glenoid inclination is significantly increased in patients with degenerative rotator cuff tears compared to healthy controls. Tendon overload secondary to increased glenoid inclination may be the primary anatomical factor contributing to the development of degenerative rotator cuff tears

Rotator cuff tears are common, with failure rates of up to 94% for large and massive tears. 1. For such tears, reattachment of the musculotendinous unit back to bone is problematic, and any possible tendon-bone repair heals through scar tissue rather than the specially adapted native enthesis. We aim to develop and characterise a novel soft-hard tissue connector device, specific to repairing/bridging the tendon-bone injury in significant rotator cuff tears, employing decellularised animal bone partially demineralised at one end for soft tissue continuation. Optimisation samples of 15×10×5mm. 3. , trialled as separate cancellous and cortical bone samples, were cut from porcine femoral condyles and shafts, respectively. Samples underwent 1-week progressive stepwise decellularisation and a partial demineralisation process of half wax embedding and acid bathing. Characterisations were performed histologically for the presence/absence of cellular staining in both peripheral and central tissue areas (n=3 for each cortical/cancellous, test/PBS control and peripheral/central group), and with BioDent reference point indentation (RPI) for pre- and post-processing mechanical properties. Histology revealed absent cellular staining in peripheral and central cancellous samples, whilst reduced in cortical samples compared to controls. Cancellous samples decreased in wet mass after decellularisation by 45.3% (p<0.001). RPI measurements associated with toughness (total indentation depth, indentation depth increase) and elasticity (1st cycle unloading slope) showed no consistent changes after decellularisation. X-rays confirmed half wax embedding provided predictable control of the mineralised-demineralised interface position. Initial optimisation trials show proof-of-concept of a soft-hard hybrid scaffold as an immune compatible xenograft for irreparable rotator cuff tears. Decellularisation did not appreciably affect mechanical properties, and further biological, structural and chemical characterisations are underway to assess validity before in vivo animal trials and potential clinical translation

Recent studies on animal models focused on the effect of preserving tendon remnant of rotator cuff on tendon healing. A positive effect by combining tendon remnant preservation and small bone vents on the greater tuberosity in comparison with standard tendon-to-bone repair has been shown. The purpose of the present clinical study was to evaluate the efficacy of biologic augmentation of arthroscopic rotator cuff repair by maintaining tendon remnant on rotator cuff footprint combined with small bone vents of the greater tuberosity. A retrospective study was conducted. All patients who underwent arthroscopic rotator cuff repair associated with small bone vents (nanofractures) and tendon footprint preservation were considered eligible for the study. Inclusion criteria were: diagnosis of full-thickness rotator cuff tear as diagnosed at preoperative magnetic resonance imaging (MRI) and confirmed at the time of surgery; minimum 24-month of follow-up and availability of post-operative MRI performed not earlier than 6 months after surgery. Exclusion criteria were: partial thickness tears, irreparable tears, capsulo-labral pathologies, calcific tendonitis, gleno-humeral osteoarthritis and/or previous surgery. Primary outcome was the ASES score. Secondary outcomes were: Quick-DASH and WORC scores, and structural integrity of repaired tendons by magnetic resonance imaging (MRI) performed six months after surgery. A paired t-test was used to compare pre- and postoperative clinical outcomes. Subgroup analysis was performed according to tear size. Significance was set at p < 0.05. The study included 29 patients (M:F = 15:14). Mean age (+ SD) of patients was 61.7 + 8.9 years. Mean follow-up was 27.4 ± 2.3 months. Comparison between pre- and postoperative functional scores showed significant clinical improvement (p < 0.001). Subgroup analysis for tear size showed significant differences in the QuickDASH score (0.04). Particularly, a significant difference in the QuickDASH score could be detected between medium and large tears (p=0.008) as well as medium and massive lesions (p=0.04). No differences could be detected between large and massive tears (p= 0.35). Postoperative imaging showed healed tendons in 21 out of 29 (72%) cases. Preservation of tendon remnant combined with small bone vents in the repair of medium-to-massive full-thickness rotator cuff tears provided significant improvement in clinical outcome compared to baseline conditions with complete structural integrity in 72% of the cases

Summary. Data of 663 patients with three different pathologies were examined. We found that using patients with significant symptoms and functional difficulty in the opposite shoulder will not bias the results of observational studies if outcomes are based on routine disability measures such as ASES or Constant-Murley scores. Introduction. Recently, using patients with bilateral limb problems as independent cases has raised concerns in orthopaedic research due to violating the assumption of independence. If observations are too similar in characteristics, they become highly correlated which leads to lowering the variance and biasing the results. Type of pathology (impingement, cuff tear, osteoarthritis) and aging are expected to affect the incidence of bilateral shoulder complaints and should be considered when examining potential bias in this area. In addition, the impact of dominant side pathology has not been investigated primarily in patients with shoulder problems. The objectives of this study were: 1) to examine the incidence of bilateral shoulder complaints and pathology on the dominant side in patients with impingement syndrome, rotator cuff tear and osteoarthritis of the glenohumeral joint, 2) to explore the role of sex and age in developing bilateral shoulder complaints, and 3) to examine the impact of bilaterality and hand dominance on pre and one year post-operative disability. Patients and Methods. This study involved review of data of patients with a diagnosis of impingement syndrome, rotator cuff tears and osteoarthritis (OA) of the gleno-humeral joint who had undergone surgery and had returned for their one year follow-up. Two outcome measures were used; the American Shoulder & Elbow Surgeons (ASES) and the Constant Murley score (CMS). Results. Data of 663 patients (317 females; 269 impingement syndrome, 290 rotator cuff tear, 104 osteoarthritis) were included in the analysis. There was a difference in the incidence of bilateral symptoms in patients with different pathologies: osteoarthritis 46%, impingement 26%, and rotator cuff tears 23% (p<0.0001). The incidence of dominant side involvement was 70%, 68% and 50% in patients with rotator cuff tear, impingement syndrome and osteoarthritis (p=0.003). Neither bilaterality nor dominant arm pathology had a negative impact on disability (p>0.05). Discussion/Conclusion. Type of pathology and aging affect the incidence of bilateral shoulder symptoms. Rotator cuff related pathologies affect the dominant side more frequently. The most interesting finding of this study was related to lack of influence of bilateral symptoms or dominant side pathology on reported disability in three different pathology groups with different prevalence of disease

Summary Statement. In this study, massive rotator cuff tears were treated using an absorbable collagen-based patch or a non-absorbable synthetic patch. Results demonstrated the efficacy of the use of the synthetic prolene patch especially for elderly patients. Introduction. The treatment of massive rotator cuff tears presents a challenging problem in shoulder surgery. Traditional repair techniques are associated with high rupture rates due to excessive tension on the repair and the presence of degenerated tendon tissue. These factors have led to attempts to reconstruct the rotator cuff with grafts, using synthetic materials or biologic tissues. The purpose of this study was to compare the efficacy of the use of pericardium patch with the use of prolene patch in the repair of extensive rotator cuff tears. Materials & Methods. A retrospective series of 180 patients, 115 men and 65 women with a mean age of 66.8 years treated for a massive rotator cuff tear from 1997 to 2008 is reported. The inclusion criteria were: patients symptomatic with pain, deficit of elevation, not responsive to the physiotherapy, tear size (massive: 2 or more tendons), minimum follow-up of 2 years since surgery, active and motivated patients. Patients were divided into three groups according to the type of treatment received: group 1 was treated with Pericardium patch, group 2 with Prolene patch, group 3 with simple suture. All groups were homogeneous. Plain radiographs, ultrasound and MRI were performed preoperatively and at 3 years. Patients were clinically evaluated using the UCLA score before surgery and at 2 months and 3 years after surgery (mean follow-up 2, 6 years). Pain was assessed by use of VAS scale, strength by the use of dynamometer. The surgical procedure (mini-open technique) was similar in all groups. Statistical analysis was conducted by one-way ANOVA between groups of treatment with Dunnett's C post-hoc correction for multiple comparisons. P-values of 0.05 or less were considered as statistically significant. Results. After 2 months the mean VAS was 6.85±1.11, 6.45±1.01, 4.9±0.9 while the mean UCLA was 11.28±1.43, 13.35±14.21, 20.85±12.77, respectively for Control, Collagen and Prolene group. After 36 months the mean VAS was 3.7±1.01, 4.05±0.98, 3.23±1.07, while the mean UCLA was 14.73±1.96, 14.86±2.08, 24.6±3.3 respectively for Control, Collagen and Prolene group. In addition, after 36 months elevation on the scapular plane was 140.75°±10.48, 141.58°±11.87, 174.75°±8.1 and abduction strength was 8.57kg±0.63, 8.82kg±0.7, 13.61kg±0.84, respectively for Control, Collagen and Prolene group. Retear rate after 12 months was 40% (24/60) for Control group, 48.33% (29/60) for Collagen group, 15% (9/60) for Prolene group. Conclusion. The use of Prolene patch as an augmentation graft in the treatment of massive rotator cuff tears is safe and, in most patients, can give a significant pain relief and improvement of range of motion and strength with few complications

Massive, irreparable rotator cuff tears occur in about 15% of patients with ruptures of the rotator cuff tendons. There is no consistently agreed management for irreparable rotator cuff tears, however, latissimus dorsi tendon transfer is a recognised technique. We aimed to review the functional outcome of patients undergoing this operation at a single tertiary referral centre. Fourteen latissimus dorsi transfer procedures in thirteen patients from May 2007 to May 2008 were retrospectively reviewed. The mean age of patients undergoing the procedure was fifty nine years. All patients were confirmed to have massive, irreparable (>5cm) rotator cuff tears as determined by MRI or ultrasound. Modified Constant scores (assessing shoulder pain, functional activity and movement) determined pre-operatively and post latissmus dorsi transfer were compared. The mean duration of follow up was 12 months. The mean Modified Constant Score (maximum = 75) improved from 23 points pre-operaively to 52 points post latissimus dorsi transfer (p < 0.05). All patients had improvement in shoulder pain following the operation. There was a trend for younger patients to have greater improvement in functional activity and shoulder movement. From our series, latissimus dorsi transfer is effective at improving functional outcomes in patients with massive, irreparable rotator cuff tears, especially in younger age groups

Treatment of massive rotator cuff tears can be challenging. Previous studies with irreparable rotator cuff tears showed good clinical results of tendon healing with the arthroscopic insertion of a protective biodegradable spacer balloon filled with saline solution between the repaired tendon and the acromion [1,2], but so far no scientific evidence has showed how the device alters pressures over the repaired tendon. This biomechanical study investigated the effects of a spacer inserted in the subacromial space on pressures over the repaired rotator cuff tendon in passive motion cycles typical for post-operative rehabilitation routines. Six human cadaveric shoulders were prepared with the humerus cut 15cm below the joint and embedded in a pot, while the scapula fixed at three points on a plate. A rotator cuff tear was simulated and repaired using a suture anchor and a Mason-Allen suture. The specimens were then mounted on a custom-made pneumatic testing rig to induce passive motion cycles of adduction-abduction (90–0°) and flexion-extension (0–40°) with constant glenohumeral and superior loads and tension is exerted on the supraspinatus tendon with weights. A pressure sensor was placed between the supraspinatus tendon and the acromion. After pressure measurements for 15 cycles of each motion type, the InSpace balloon (OrthoSpace, Inc, Israel) was inserted and the specimens tested and pressure measured again for 15 cycles. Statistically significant changes in peak pressures were then measured before and after balloon. Peak pressures were measured near 90 degrees abduction. No statistical differences were observed for internal-external rotation before and after balloon-shaped subacromial spacer was inserted. Mean pressures in abduction-adduction were significantly reduced from 121.7 ± 9.5 MPa to 51.5 ± 1.2 MPa. Peak pressures after repair were 1171.3 ± 99.5 MPa and 1749.6 ± 80.7 MPa in flexion-extension and abduction-adduction motion, respectively, and significantly decreased to 468.7 ± 16.0 MPa and 535.1 ± 27.6 MPa after spacer insertion (p<0.0001). The use of the spacer above the repaired tendon reduced peak pressures and distributed them more widely over the sensor during both abduction-adduction and flexion-extension motions and therefore can reduce the stress on the rotator cuff repair. The InSpace system may reduce the pressure on the repaired tendon, thus potentially protecting the repair. Further studies to investigate this phenomenon are warranted, in particular relating these changes to shoulder kinematics following tear repair and spacer insertion

Introduction. Rotator cuff healing after an arthroscopic repair is discussible because of the high incidence of failures. Among biologic augmentations currently used, platelet-rich plasma (PRP) is one of the most applied, supposed to enhance and accelerate the healing process in different musculoskeletal disorders. However, the evidence supporting its successful administration is still lacking, especially in the field of the rotator cuff repair. Our purpose is to clarify if the recovery is accelerated and the integrity of repaired construct is increased in patients undergoing PRP injections after arthroscopic repair of the rotator cuff. Patients & Methods. Thirty-eight patients with full-thickness rotator cuff tears have been enrolled after they had been informed about the use of PRP and the timing of its application postoperatively. Seventeen patients underwent arthroscopic rotator cuff repair and PRP injections (3 injections at 10 days each other), 21 underwent arthroscopic rotator cuff repair without PRP injections. Outcomes were assessed preoperatively, at 3, 6, 12, and minimum 16 months after surgery (average 17.7 +/− 1.7 months). Constant system, the University of California at Los Angeles (UCLA) system and a Visual Analogue Scale (VAS) scale were used; range of motion and strength in all planes were also assessed. The healing of the repair was assessed at magnetic resonance imaging at a minimum follow up of 6 months from surgery. All patients had the same rehabilitation protocol. Results. Platelet-rich plasma gel application after to arthroscopic rotator cuff tear repairs did not accelerate recovery with respect to pain, range of motion, strength, functional scores, or overall satisfaction as compared with conventional repair at any time point. There was no difference between the 2 groups after 3, 6, 12, months and at final follow up. The follow-up MRI showed no significant difference in the healing rate of the rotator cuff tear. In addition, magnetic resonance imaging, at a minimum of 6 months after surgery, demonstrated a retear rate of 23.5 % in the PRP group and 19% in the conventional group, there was no statistical significance between the groups (P = .658). Discussion/Conclusion. Although PRP application after arthroscopic repair of the rotator cuff has no effects on clinical recovery and structural integrity, it reduces the postoperative occurrence of shoulder stiffness. Further studies should support these findings

This protocol describes a pragmatic multicentre randomised controlled trial (RCT) to assess the clinical and cost effectiveness of arthroscopic and open surgery in the management of rotator cuff tears. This trial began in 2007 and was modified in 2010, with the removal of a non-operative arm due to high rates of early crossover to surgery. . Cite this article: Bone Joint Res 2014;3:155–60

Introduction. The healing of rotator cuff injuries poses significant challenges, primarily due to the complexity of recreating the native tendon-to-bone interface, characterized by highly organized structural and compositional gradients. Addressing this, our innovative approach leverages bioprinted living tissue constructs, incorporating layer-specific growth factors (GFs) to facilitate enthesis regeneration. This method aims to guide in situ zonal differentiation of stem cells, closely mirroring the natural enthesis tissue architecture. Method. Our strategy involves the utilization of advanced bioprinting technology to fabricate living tissue constructs. These constructs are meticulously designed with embedded microsphere-based delivery carriers, ensuring the sustained release of tenogenic, chondrogenic, and osteogenic growth factors. This layer-specific release mechanism is tailored to promote the precise differentiation of stem cells across different regions of the construct, aligning with the gradient nature of enthesis tissues. Result. In vitro studies demonstrated that our layer-specific tissue constructs significantly outperformed basal constructs without GFs, achieving region-specific differentiation of stem cells. More critically, in a rabbit model of rotator cuff tear, these bioprinted living tissue constructs expedited enthesis regeneration. Key outcomes included improved biomechanical properties, enhanced collagen deposition and alignment, and the formation of a gradient fibrocartilage interface with aligned collagen fibrils. After 12 weeks, the constructs achieved an ultimate load failure of 154.3 ± 9.5 N resembling that of native enthesis tissues, marking a notable achievement in tissue engineering. Conclusion. Our exploration introduces a viable and innovative strategy for engineering living tissue constructs that exhibit region-specific differentiation capabilities. This approach holds significant promise for the functional repair of gradient enthesis tissues, potentially revolutionizing the treatment of rotator cuff injuries by closely replicating the natural tendon-to-bone interface, thus offering a promising avenue for future clinical applications

Glutamate regulates the expression of apoptosis-related genes and triggers the apoptosis of fibroblasts in rotator cuff tendons. Subacromial bursitis is always accompanied by symptomatic rotator cuff tear (RCT). However, no study has been reported on the presence of glutamate in subacromial bursa and on its involvement of shoulder pain in patients who had RCT. The purposes of this study were to determine whether the glutamate expression in subacromial bursa is associated with the presence of RCT and with the severity of shoulder pain accompanying RCT. Subacromial bursal tissues were harvested from patients who underwent arthroscopic rotator cuff tendon repair or glenoid labral repair with intact rotator cuff tendon. Glutamate tissue concentrations were measured, using a glutamate assay kit. Expressions of glutamate and its receptors in subacromial bursae were histologically determined. The sizes of RCT were determined by arthroscopic findings, using the DeOrio and Cofield classification. The severity of shoulder pain was determined, using visual analog scale (VAS). Any associations between glutamate concentrations and the size of RCT were evaluated, using logistic regression analysis. The correlation between glutamate concentrations and the severity of pain was determined, using the Pearson correlation coefficient. Differences with a probability <0.05 were considered statistically significant. Glutamate concentrations showed significant differences between the torn tendon group and the intact tendon group (P = 0.009). Concentrations of glutamate significantly increased according to increases in tear size (P < 0.001). In histological studies, the expressions of glutamate and of its ionotropic and metabotropic receptors have been confirmed in subacromial bursa. Glutamate concentrations were significantly correlated with pain on VAS (Rho=0.56 and P =0.01). The expression of glutamate in subacromial bursa is significantly associated with the presence of RCT and significantly correlated with its accompanying shoulder pain. Acknowledgements: This research was supported by the Basic Science Research Program, through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2015R1D1A3A01018955 and 2017R1D1A1B03035232)

Background. High re-rupture rates following repairs of rotator cuff tears (RCTs) have resulted in the increased use of repair grafts to act as temporary scaffolds to support tendon healing. It has been estimated that thousands of extracellular matrix repair grafts are used annually to augment surgical repair of rotator cuff tears. The only mechanical assessment of the suitability of these grafts for rotator cuff repair has been made using tensile testing only, and compared grafts to canine infraspinatus. As the shoulder and rotator cuff tendons are exposed to shearing as well as uniaxial loading, we compared the response of repair grafts and human rotator cuff tendons to shearing mechanical stress. We used a novel technique to study material deformation, dynamic shear analysis (DSA). Methods. The shear properties of four RCT repair grafts were measured (Restore, GraftJacket, Zimmer Collagen Repair and SportsMesh). 3mm-sized biopsy samples were taken and subjected to DSA using oscillatory deformation under compression to calculate the storage modulus (G') as an indicator of mechanical integrity. To assess how well the repair grafts were matched to normal rotator cuff tendons, the storage modulus was calculated for 18 human rotator cuff specimens which were obtained from patients aged between 22 and 89 years (mean age 58.8 years, with 9 males and 9 females). Control human rotator cuff tendons were obtained from the edge of tendons during hemiarthoplasties and stabilisations. A 1-way ANOVA of all of the groups was performed to compare shear properties between the different commercially available repair grafts and human rotator cuff tendons to see if they were different. Specific comparison between the different repair grafts and normal rotator cuff tendons was done using a Dunn's multiple comparison test. Results. We report a significant difference in the shear moduli of all four rotator cuff repair grafts (P<0.0001, 1 way ANOVA, Kruskall-Wallis test). 2 of the grafts, Zimmer Collagen Repair and SportMesh, were not significantly different when compared to rotator cuff tendons and were found to have comparable shear mechanical properties (P > 0.05, Dunn's multiple comparison test). The other repair grafts, GraftJacket and Restore, had a significantly lower storage modulus when compared to human rotator cuff tendons. Conclusions. With increasing numbers of repairs of rotator cuff tears, and augmentation of these repairs, there is a need to understand the mechanical and biological properties of the both repair grafts and the tendons they are designed to augment. At present there is no clear definition of the ideal mechanobiological properties of rotator cuff repair patches. Current rotator cuff repair grafts display a wide variation in their shear mechanical properties, and how closely they are matched to the mechanical properties of human rotator cuff tendons. It is hoped that this study may help to guide surgeons in deciding on the most appropriate rotator cuff tendon repair graft

Introduction. Supraspinatus and infraspinatus tears (Massive Rotator Cuff Tear- MRCT) cause compensatory activation of the teres minor (TM) and subscapularis (SubS) to maintain humeral head alignment. This study measures force changes in TM and SubS using a dynamic shoulder testing setup. We hypothesize that combining superior capsule reconstruction (SCR) and lower trapezius tendon (LTT) transfer will correct rotator cuff forces. Methods. Eight fresh-frozen human shoulder specimens from donors aged 55-75 (mean = 63.75 years), balanced for gender, averaging 219.5 lbs, were used. Rotator cuff and deltoid tendons were connected to force sensors through a pulley system, with the deltoid linked to a servohydraulic motor for dynamic force measurement. The system allowed unrestricted humeral abduction from 0 to 90 degrees. Results. Teres Minor (TM):. -. Control: 7.43 N (SD = 1.66). -. SS tear: 5.46 N (SD = 1.45). -. MRCT: 3.94 N (SD = 1.43). -. LTT post-MRCT: 5.85 N (SD = 1.13). -. SCR post-MRCT: 4.68 N (SD = 0.71). -. Combined LTT+SCR: 6.43 N (SD = 1.24). -. TM force reduction: 26.51% post-SS tear, 46.97% from intact to MRCT, 63.20% increase with LTT+SCR. Subscapularis (SubS):. -. Control: -0.73 N (SD = 0.43). -. SS tear: -0.46 N (SD = 0.36), 36.99% increase. -. MRCT: 0.96 N (SD = 0.47), 31.51% increase. -. LTT post-MRCT: -0.32 N (SD = 0.47), 66.67% reduction. -. SCR post-MRCT: -0.28 N (SD = 0.16), 70.83% reduction. -. Combined LTT+SCR: -0.66 N (SD = 0.32), 31.25% reduction. Non-parametric Friedman's ANOVA showed overall statistical significance for TM (P = 1.083×10. -6. ) and SubS (P = 4.77×10. -4. ). Conclusion. The cadaveric model assesses rotator cuff compensations, showing significant TM force reductions following rotator cuff tears and improvements with LTT and SCR, particularly when combined. SubS exhibited negative force during normal abduction but compensated during MRCT, returning to normal values post-LTT and SCR

Introduction. It is an example of tendon to bone healing of rotator cuff tears. Low Level Laser Therapy (LLLT) is used in pain literature, pain palliation, tendinopathies, osteoarthritis treatment, implant osteointegration in jaw surgery, wound healing, fracture healing, tendon healing, nerve healing. But; there is not a study on tendon-bone healing. It is aimed to investigate the effects of tendon to bone healing with the rotator cuff experimental tear model. Material and Methods. 60 Wistor Albino Rat right shoulders were used in our project in four groups. Effectiveness of the study in each study group to increase and use the minimum number of animals that would be significant it was planned to use 15 (6 histology + 9 biomechanical) subjects. In our study, there are 4 groups in total. 1. Group 4. Week sacrified control group 2. Group 4. Week sacrificed LLLT group 3. Group 8. Week sacrified control group 4. Group is postoperative LLLT group. The 4 round SSP tendons have been cut with a full course. A total of eight sessions of biostimulation were performed with 24 j energy per session. Biomechanical tensile test and histopathological examination were performed on rats sacrificed at 4 and 8 weeks. In histological examination, cellularity at the repair site with hemotoxylin-eosin staining, extracellular matrix localization with Masson trichrome staining and fibrosis, TRAP (Tartrate Resistance Acid Phosphatase) and osteoclast activity, collagen fibril organization with picrochucine were evaluated. In immunohistological examination, proliferation activity was evaluated by CD-31 (Abcam, Cambridge, MA, USA) through vascular endothelial cells, Ki-67 (Tucson, AZ) and tendon proliferation index. Failure load for comparison of biomechanical stability between groups drawing will be done. Biomechanical pulling applications Linear pulling force over tendon It will be realized by applying. Last failure load (Newton), elongation (mm) and hardness values was recorded. Results. Two rats died in the postoperative first group and one rat died in the other groups. Six animals from each group were examined histopathologically. While the mean of stifness was higher in the patient who underwent LLLT at the 4th week biomechanically compared to the control group, there was no difference in the 8th week between the control group LLLT biomechanically. Histologically, the group with LLLT at 4 weeks showed increased fibroblastic activity and osteoclastic activity, but at 8 weeks there was no significant difference. Discussion. There are studies on the benefits of biostimulation with LLLT in fracture healing, implant integration, wound healing, tendon healing. Biostimulation experiments with LLLT for tendon healing were evaluated in rotator cuff healing as they were not available in literature. Especially early contributions were thought to be beneficial for postoperative rupture